This week's challenge underscored the power of the banh mi Vietnamese sandwiches that are sold by the Nom Nom truck:

The three remaining food trucks pulled into Jonesborough, Tenn. To date, the trucks have been selling their wares in cities that are pretty hip to the whole food truck thing, like L.A. and Fort Worth, Texas. But Jonesborough, a quaint little town of 5,000, had never seen a food truck. Would the townspeople even care? Would they go for the tried-and-true burgers sold by the L.A.-based Grill 'Em All Truck or experiment with the French flair of the cuisine sold by the San Francisco-based Spencer on the Go Truck? Well, it looked like all 5,000 townspeople showed up to find out what this food truck fuss was all about -- and it seemed like nearly all of them got in line for Nom Nom, even though some had no idea what a Vietnamese sandwich was, and couldn't even pronounce banh mi with some gentle coaching.

Then came this week's "Truck Stop" challenge, the best one yet. Host Tyler Florence brought the remaining contestants to, believe it or not, Old Man Johnson's Farm, down by the river. There, he told the contestants that food trucks are nothing new, they just used to be called chuck wagons. And this week's challenge put the contestants' cooking skills to test in a game that so far has been dominated by Nom Nom's brilliant marketing skills: They had to make a five-course meal over an open fire, just like in the old days. Well, the twist "worked." Nom Nom crashed and burned, and Grill Em All ended on top. The prize was a stunner: The opportunity to park the truck at a local auto show, where they were guaranteed to do a solid night's business, while Nom Nom and Spencer had to look for customers in Jonesborough, which basically shuts down each night by dusk.

Given this turn of events, it looked like Grill 'Em All had this week won. But then came the shocking totals:

Nom Nom still came out on top, and not by a little: They earned a stunning $3,117. Despite the advantage earned by Grill 'Em All, the burger truck earned just $2,763. And, even more surprising, Spencer lost by just $37. They earned $2,726, which put them in last place, and out of the game.

I'm STILL trying to figure out the results of this challenge. The burger truck was slammed with orders during the auto show. How could they still end up neck-and-neck with Spencer? And how could they end up so far behind Nom Nom? It all speaks to the power of the Nom Nom.

One thing is for sure: It will be a fitting finale this week. It's an L.A. versus L.A. showdown in New York City. Who do you think will win? Nom Nom, for the sweep? Or will the Big Apple flip for Grill 'Em All's big burgers?